PM2.5, tiny particles suspended in the air that can lodge into lungs and cause diseases, jumped to dangerous levels in the Indian capital on Sunday, according to data measured by the board’s air-quality stations in the city.

In some areas, such as the Pitampura suburb of north Delhi, PM2.5 levels increased to 1,238 on Sunday, compared with 435 the same day of the festival a year earlier. The World Health Organization recommends that PM2.5 is kept below 10 as an annual average. It says exposure to average annual concentrations of PM2.5 of 35 or above is associated with a 15% higher long-term mortality risk.

India’s environment ministry said that the burning of solid waste and crops, vehicular emissions and dust from construction sites are major contributors to the city’s smog.

The New Delhi skyline on Oct. 28, 2016, top, and a day after Diwali festival on Oct. 31, 2016, bottom.
Photo:
Altaf Qadri/Tsering Topgyal/Associated Press

It said in a news release that the capital’s problem was accentuated on Sunday by relatively low winds and lower temperatures, meaning that pollutants weren’t dispersed.

Dr. Dipankar Saha, scientist and in-charge of the air laboratory at the Delhi-based pollution control board said that firecrackers and fireworks set off during the Diwali celebrations “may have added” to the city’s pollution levels.

“We need to make people aware that their activities should not release more emission when our air is already so polluted,” he said.

The United Nations Children’s Fund in a report entitled “Clean the Air for Children,” released Sunday, said that nearly 20% of the world’s children who live in India risked developing life-long health complications due to air pollution and in some cases even death.

“Children are uniquely vulnerable to air pollution – due both to their physiology as well as to the type and degree of their exposure,” said the report.

That is because they breathe twice as fast as adults, taking in more air and pollutants which can adversely affect their growth and immune system.

The report said that outdoor air pollution in India exceeds nearly six times that of limits considered safe internationally, while more than half of the country’s population still burns solid fuels for cooking and heating, often the causes of ill health and early death in children.